seeking broken sound driver advice

I'm having trouble playing some sound files, and
don't know what to try next.

For reference, I'm running:

o Red Hat Linux 7.1 on a Dell, kernel 2.4.2-2
o Turtle Beach Montego A3D 64-Voice PCI Audio Card
o An OSS sound card driver I paid money for

(Have I left out anything relevant?)

The main symptom is this:

o I use xmms to play MP3 files. It used to work without
problems. Suddenly, for some unexplained reason, when
I load an MP3 into xmms, it plays a two and a half
minute piece of music in about fifteen seconds.

This is not broken:

o I can insert audio CDs and play them normally.

o I can play WAV files from a command line using play filename.wav

o Real Audio Player works, although it's sometimes
funky. (I probably need to reset the transmission
speed.)

This is what I've done to try to fix it:

o Reinstalled the sound driver.

o Installed a newer version of xmms (1.2.6, whereas I
think 1.2.3 was part of the RH 7.1 distribution. Or
else I picked it up in RPM form from FreshMeat a long
time ago, when it was at version 1.2.3.)

It's been this way for months. I've just procrastinated
about trying to fix it. But someone sent me an MP3 of
some of his work that I very much want to hear, so it's
time to pop the task to the top of the stack.

I have *not* tried to get a newer version of the driver
and install it. It shouldn't be necessary, because to
my knowledge I didn't do anything to change the state
of the system. One day it worked, the next day it
didn't.

Does anyone have any hints as to where I go from here?

Thank you.

--
Lynn David Newton
Phoenix, AZ